Blank Mask and Method for Fabricating Photomask Using the Same

Abstract

A photomask is formed on an etch target layer of a transparent substrate using a blank mask that includes a carbon layer and an oxide layer. The carbon layer and the oxide layer are disposed on the etch target layer. The oxide layer is formed into an oxide layer pattern by photolithography for selectively exposing the etch target layer. A carbon layer pattern is formed by etching the carbon layer using the oxide layer pattern. An etch target layer pattern is formed by etching the etch target layer using the carbon layer pattern as a hard mask. Therefore, a sufficient thickness of the carbon layer can be etched using a thin oxide layer pattern employing the etch selectivity characteristics of the oxide layer and the carbon layer. Furthermore, the etch target layer pattern can have a predetermined vertical profile. The carbon layer pattern can be removed using oxygen plasma without damaging the underlying etch target layer pattern.

1 . A blank mask comprising an etch target layer, a resist layer, and a carbon layer disposed between the etch target and resist layers. 
   
   
       2 . The blank mask of  claim 1 , wherein the etch target layer is a light blocking layer. 
   
   
       3 . The blank mask of  claim 1 , wherein the etch target layer comprises a phase shift layer and a light blocking layer. 
   
   
       4 . The blank mask of  claim 1  further comprising an oxide layer disposed between the carbon and resist layers. 
   
   
       5 . The blank mask of  claim 4 , wherein a ratio of an etching rate of the oxide layer to an etching rate of the carbon layer is about one to ten. 
   
   
       6 . The blank mask of  claim 4 , wherein the oxide layer is about nine to ten time as thin as the carbon layer. 
   
   
       7 . A method for fabricating a photomask, the method comprising:
 forming a light blocking layer and a carbon layer on a transparent substrate;   forming a carbon layer pattern by selectively etching the carbon layer through a first etch process using a resist layer pattern that selectively exposes the carbon layer;   etching the light blocking layer through a second etch process, using the carbon layer pattern as a hard mask, to form a light blocking layer pattern; and,   removing the carbon layer pattern.   
   
   
       8 . The method of  claim 7 , wherein the light blocking layer comprises chromium. 
   
   
       9 . The method of  claim 7  further comprising forming an oxide layer on the carbon layer. 
   
   
       10 . The method of  claim 9 , wherein a ratio of an etching rate of the oxide layer to an etching rate of the carbon layer is about one to ten. 
   
   
       11 . The method of  claim 7 , wherein the first etch process is a dry etch process using oxygen plasma. 
   
   
       12 . The method of  claim 7 , wherein the second etch process is a dry or wet etch process. 
   
   
       13 . The method of  claim 7 , wherein the removing of the carbon layer pattern is performed using oxygen plasma. 
   
   
       14 . A method for fabricating a photomask, the method comprising:
 forming a phase shift layer, a light blocking layer, and a carbon layer on a transparent substrate;   selectively etching the carbon layer through a first etch process, using a first resist layer pattern capable of selectively exposing the carbon layer, to form a carbon layer pattern;   selectively etching the light blocking layer and the phase shift layer through a second etch process, using the carbon layer pattern as a hard mask, to form a light blocking layer pattern and a phase shift layer pattern;   removing the carbon layer pattern;   forming a second resist layer pattern capable of selectively exposing the transparent substrate on which the light blocking layer pattern and the phase shift layer pattern are formed;   etching the light blocking layer pattern exposed by the second resist layer pattern; and,   removing the second resist layer pattern.   
   
   
       15 . The method of  claim 14 , wherein the phase shift layer comprises molybdenum silicon oxide nitride, and the light blocking layer comprises chromium. 
   
   
       16 . The method of  claim 14  further comprising forming an oxide layer on the carbon layer. 
   
   
       17 . The method of  claim 16 , wherein a ratio of an etching rate of the oxide layer to an etching rate of the carbon layer is about one to ten. 
   
   
       18 . The method of  claim 14 , wherein the first etch process is a dry etch process using oxygen plasma. 
   
   
       19 . The method of  claim 14 , wherein the second etch process is a dry or wet etch process. 
   
   
       20 . The method of  claim 14 , wherein the removing of the carbon layer pattern is performed using oxygen plasma.